第二章表面与界面现象.ppt

第二章表面及界面现象 2.1表面及界面现象 2.2吸附、润湿、乳化、增溶及相关应用 2.3界面双电层 Interface and surface Interface and surface Interface and surface Interface and surface Interface and surface solid–gas solid–liquid solid1-solid2 liquid–gas liquid1–liquid2 Interface and surface Interface and surface 表面和界面(surface and interface) 表面和界面(surface and interface) 表面和界面(surface and interface) 表面和界面(surface and interface) 表面和界面(surface and interface) properties of liquid surface Elasticity: Liquid surfaces tend to contract to the smallest possible surface area Violent agitation: water molecules on surface jump in and out of the surface very rapidly Adsorption: concentration difference between surface and bulk in solution properties of liquid surface Surface tension: is the force that operates inwards from the boundaries of its surface perpendicularly, tending to contract and minimize the area of the surface. Capillary action:is a physical effect caused by the interactions of a liquid with the walls of a thin tube. properties of solid surface Impurity:A solid surface is mostly contaminated with foreign matter as a thin layer above thetopmost surface molecules (or atoms), unless very special precautions are taken. properties of solid surface surface roughness: uneven Surface roughness is defined as the ratio of real surface area to the plan area, and it is larger than 1 for all practical surfaces. properties of solid surface chemically heterogeneous: due to the presence of different chemical groups, impurities or crystals at the surface. properties of solid surface The chemical heterogeneity of a surface is an important property in industry affecting catalysis, adhesion, adsorption, wettability, biocompatibility, printability and lubrication behavior of a surface, and it must be determined analytically when required. properties of solid surface it has become possible to image surface atoms with the advent of scanning probe microscopy techniques, such as atomic force microscopy (AFM), and scanning